Principles and Standards for School Mathematics
Number and Operations Standard
Compute fluently and make reasonable estimates
Expectations (3 - 5)
develop fluency in adding, subtracting, multiplying, and dividing whole numbers;
select appropriate methods and tools for computing with whole numbers from among mental computation, estimation, calculators, and paper and pencil according to the context and nature of the computation and use the selected method or tools.
Solve problems that arise in mathematics and in other contexts
Apply and adapt a variety of appropriate strategies to solve problems
Reasoning and Proof Standard
Make and investigate mathematical conjectures
Develop and evaluate mathematical arguments and proofs